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Trans. Acad. Sci. of St. Louis. 



nensis Rob. ?, s.; (14) H. confusus Sm. ?, 8. & c. p.; (15) H. stultus Cr. 

 9, c. p., freq. 



Diptera— Conopidae: (16) Stylogaster biannulata Say, s., freq. ; Syrphi- 

 dae (17) Pipiza pistica Will., f. p., one; (18) Baccha fuscipennis Say, f . p., 

 one. 



Lepidoptera— Rhopalocera: (19) Papilio troilus L., s., one; (20) Euda- 

 mus bathyllus S. & A., s. 



Viburnum L. — In V. opulus, Sprengel (1) explained the 

 significance of the more conspicuous, sterile marginal flowers. 

 Delpino (3) includes V. opulus and lantana in his Tipoidran- 

 geino, along with some species of Hydrangea, Cornus and 

 Sambucus. He regards the inflorescences as favoring the 

 visits of beetles. Sprengel observed that V. opidus was 

 especially sought by beetles, and these form a majority of the 

 insect visitors observed by Mailer (2, 8), though he consid- 

 ered flies to be the most efficient pollinators. In Illinois I 

 find a larger proportion of beetles on V. pubescens than on any 

 other flower except Spiraea aruncus. After beetles, species 

 of Andrena and Empis are next in abundance. The blooming 

 time occurs when these insects are frequent. In the Tyrol 

 Schulz (12) found V. lantana to be abundantly visited by 

 Diptera, Hymenoptera and Coleoptera. In the Berlin Garden 

 Loew (11) saw it visited by Bibio laniger. The following 

 table gives the visitors which have been identified : — 



In V. opulus, according to Muller (2), the flowers are 

 crowded in a flat corymb. They are white, with short tubes, 

 expanded borders, rather long stamens and short styles. 

 Nectar is secreted by the upper surface of the ovary. Insects 



